.Net Nullable - how do you use it?

If you declare a variable (for example) DateTime? myDate, I can't seem to do anything with it unless I explicity cast it back to a DateTime:
DateTime? myDate = objectWhichMayMakeNullOrDateTime.GetVal();
if(myDate!=null)
{
     string myString=    myDate.ToString("hh:mm"); //fails
}
What good is the nullable operator here? What is a better way of doing this?
Silas2Asked:
Who is Participating?
 
Naman GoelSoftware engineer 1Commented:
0
 
Naman GoelSoftware engineer 1Commented:
use like following :


DateTime? myDate = objectWhichMayMakeNullOrDateTime.GetVal();
if(myDate!=null)
{
     string myString=    myDate.Value.ToString("hh:mm"); //fails
}

or use HasValue property for this
            if (myDate.HasValue)
            {
                string myString = myDate.Value.ToString("hh:mm"); //fails
            }


refer to following MSDN link for detail of its usage.
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Carl TawnSystems and Integration DeveloperCommented:
Nullable objects are generally used for scenarios where an object may not have a value. Specifically for a DateTime? it marks the difference between the variable having a default value and not having a value at all.

The nullable types are generic types and are therefore objects in themselves. You use the "Value" property to return the actual value of the variable and the "HasValue" property to determine if the value is NULL or not.
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Sudhakar PulivarthiProject Lead - EngineeringCommented:
Hi,

objectWhichMayMakeNullOrDateTime.GetVal() method should return DateTime? and check what it is returning.
usually a value type should have a value. it cannot have null except string (which is not a value type in real terms) When in our app we come across a requirement to know whether or not user has provided a value (During xml interfacing/datatable). We use Nullable which accepts one more additional value null

Thuse int? will accept 0, integer and also null. When user has not provided a value then we can set it as null. In its absence we have option to set some value like 0,-1 which is also a valid integer.

Check whether its your requirement is like the above one then u go a had in using it, else unnessarily it hurts performance in boxing/unboxing the values.

Refer: http://msdn.microsoft.com/en-us/library/b3h38hb0.aspx
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